Railway traffic controlling apparatus



June 27, 1944. H, A. WALLACE 2,352,293

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Sept. 17. 1941 3 Sheets-Shec 1 SEQQA Kw 52% Na MN MN a aw b N m Egg .N 1 R xmbwg vwwgx g E m m .MQQEN \N i A p w Sh hw 5% Wm w 0 E w N y w E B 4 m 3 Sheets-Sheet 2 Herbert l 3s mm? A June 27, 1944. H. A. WALLACE RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Sept. 17. 1941 3 Sheets-Sheet 3 H. A. WALLACE.

Filed Sept. 17. 1941 RAILWAY TRAFFIC CONTROLL ING APPARATUS vJune 27, 1 944.

LL J 51 a an wm 5. g ml g w gNL NN v xi M. {T 7 7% i 4 u E Q m @J ASS WEN vg kg mu u Patented June 27, 1944 RAILWAY TRAFFIC CONTROLLING APPARATUS Herbert A. Wallace,- Edgewood, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application September 17, 1941, Serial No. 411,161

12 Claims.

My invention relates to railway traffic controlling apparatus, and it has particular reference to the organization of such apparatus intorail- Way trafilc controlling systems incorporating means for controlling railway traffic controlling devices or functions such as signals and switches and incorporating means for electrically locking such functions. More particularly, my invention relates to systems of the class named wherein both the traffic controlling functions and the electric locking functions are controlled by using the track rails as transmission conductors, thus obviating the necessity of line wires.

It has been proposed heretofore to control either, but not both, trafiic controlling functions or electric locking functions without using line wires by locating the controlling trafilc respon: sive means adjacent either the trailic or the looking function respectively. Approach locking of a track switch and control of the associated distant signal has been attained, for example, by locating the track relay of the approach section at the signal for controlling the signal without line wires, and by. extending a line circuit from the signal location to the switch location for controlling the approach locking. Alternately, the approach track relay may be located adjacent the home signal or the track switchlocation, thereby enabling the approach locking to be effected without line wires, but involving a line wire circuit extending from the relay location to the approach signal at the opposite end of the section to control such signal. Similarly, signal indication locking wherein the proper restrictive indications of distant signals leading up to an interlocking are checked prior to releasing the locking of a signal lever, and traflic locking wherein signal levers controlling traffic in either direction over a single track stretch are locked to prevent the clearing of opposing signals when the stretch is signaled for a traflic movement in one direction, both generally involve the use of line wire circuits to control either the locking or the traffic controlling functions.

An object of my invention is to obviate the necessity for line wire circuits in systems of the above described class, by utilizing the track rails as transmission conductors for efiecting the control of both the electric locking and the traific controlling functions.

Another object is to provide a trafllc controlling system in which no line wires are involved in the control of a distant signal and. approach looking of the function associated with such signal.

Another object is to provide railway trafiic controlling systems in which no line wires are required to establish control of a distant signal,

approach locking of a function associated with each signal and remotely located with respect thereto, and approach annunciators or indicators at the remotely located associated function.

Another object is to provide railway traflic controlling systems in which no line wires are involved in approach looking a function and in checking the position of a distant signal asso{ ciated with such function prior to releasing the lockin of the function. V I

Another object is to incorporate into systems of the above described class utilizing no line wires, approach control of the home signal associated with the approach locked function.

Another object is to provide railway traific controlling systems wherein trafiicflocking between two control towers at the opposite ends of a stretch is efiected without using line wires by employing the track rails as transmission conductors. V l

Another object is to provide novel and improved railway traflic controlling systems wherein trafiic locking means at two remotely spaced control towers, and indicationsrelating to proposed traflic movements over the controlled stretch intermediate the towers, are controlled without using line wires by utilizing the track rails as transmission conductors.

Another object is to provide novel and improved railway traflic controlling systems incorporating means for providing and utilizing a relatively large number of codes applied to the track rails of a stretch for controlling without using line wires the locking of remotely located functions, the operation and approach control of associated control functions, and the operation of indicators or other devices for conveying information. I 7

Another objectis to provide novel and improved railway trafiic controlling systems of the above described class provided for a stretch of track and arranged so as to efiect control of train-carried apparatus on a train irrespective of the direction'of movement of the train over the stretch.

Another object is to provide novel and improved railway trafilc controlling systems.

The above-mentioned and other important objects and characteristic features of my invention which will become readily apparent from the following description, are attained in accordance with my invention by controlling the locking of a control function located adjacent one end of a over a track circuit which also includes the rails of the section and which is supplied with current from a source at the one end of the section.

My invention also resides in the organization and arrangement of apparatus into railway traiiic 5 controlling systems involving in various combinations the control of functions, the locking of remotely located associated functions, the control of train-carried apparatus, and approach control of functions and annunciators, as will be made clear in the following description.

I shall describe two forms of apparatus canbodying my invention and shall then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a dia grammatic view illustrating one embodiment of my invention applied to the control of operation and locking of functions associated with a stretch of railway track. Figs. 2a and 2b are diagrammatic views which when placed end to end with Fig. 20: on the left, represent a modified arrangement embodying my invention of the apparatus of Fig. 1. Fig. 3 is a diagrammatic view illustrating a modified arrangement embodying my invention of a portion of the apparatus shown in Fig, 2b. In each of the several views, similar reference characters have been employed to designate corresponding parts.

Referring to Fig. 1, the reference characters I and la designate the track rails of a stretch of railway track X which is connected to a siding or spur track Y by means of a track switch W,

and over which track X traific normally moves in the eastbound direction as indicated by an associated arrow in the drawings, or from left to right as viewed in the drawings. Track X is divided by the usual insulated joints 2 into a plurality of successive adjoining track sections DE, EF and F-G. Sections D--E and EF will be referred to hereinafter as approach sections, while section FG in which the switch W is located, will be referred to as a detector section.

Each of these sections is provided with a track circuit, the circuits for sections D--E and FG being provided in the usual manner by'connecting a suitable source of track circuit energy, such as a track battery TB, across the rails at one end of the section and connecting a track relay, designated by the reference character TR with a suitably distinguishing suffix, to the'rails at the other end of the section. Section EF is provided with two track circuits formed by supplying to one end of the section coded track circuit current of a distinctive character, by supplying to the other end coded track circuit current having distinctively differentcharacteristics, and by providing each end of the section with a track relay, designated by the reference character TR with a suitably distinguishing sufiix, responsiv only to current of the character supplied at the opposite end of the section, as will be made clear presently.

Trafiic on track X moving in the normal direction is governed by signals SE and SF located respectively at opposite ends of section EF. These signals may be of any desired type such as position light, color light, semaphore, searchlight, etc., and for th purposes of this description it will be assumed that the signals are of the threeposition semaphore type. Signal SF comprises two signal units UI and U2 located on a single mast. Each unit U of signal SE is provided with a signal lamp, designated by the reference character L with a suitably distinguishing suffix corresponding to the suffix employed in the reference character of the associated signal unit, which lamps are normally dark but which become energized in a manner to be explained hereinafter upon the approach of a train to the signal. Each unit of signal SF controls an associated circuit controller, designated by the reference character J with a sufiix corresponding to the suffix employed in the reference character of the associated signal unit, comprising a contact member If operated by the associated signal mechanism and engaging a fixed contact l2 when and only when the associated signal mechanism is in its most restrictive or stop position. Controller J I also comprises a second movable contact member l3 operated by the associated mechanism of unit Ul into engagement with a fixed contact l4 when unit Ul is in its stop position, and engaging another contact l5 when unit Ul is in either its caution or its clear position. Signal SE comprises a single semaphore unit operating a circuit con troller J3 having a movable contact member l6 operated by the signal mechanism into engagement with a contact member 18 when the associated signal mechanism is in its least restrictive or clear condition and into engagement with another contact member l'i when the associated signal mechanism is in or between its restricting or caution and stop positions. Signal SF governs the movement of traific over switch W and section FG and will be referred to hereinafter as a home signal, while signal SE governs traffic approaching signal SF and switch W and will be referred to hereinafter as an approach or distant signal.

, Signal SF is a semi-automatic signal controlled in the usual manner by traffic conditions in section F--G and by a manually operable control member V, which may, for example, be a signal lever of an interlocking machine. Lever V normally occupies a normal position N, and is operable to a reverse position R wherein it is conditioned to cause the operation of signal unit U! of signal SF from its stop condition. Suitable locking means, such as, for example, a locking segment l9 secured to lever V and engageable by a locking dog 2|, provided for lever V prevents movement of the lever from its reverse position R into its full normal position N unless a lock magnet M is energized to actuate locking dog 2| out of engagement with segment I8. Lever V ordinarily is interlocked with the control lever of the associated switch W in such manner as to permit movement of the switch lever to take place only when lever V is in its full normal position N. This locking may be either mechanical or electrical, and such locking apparatus toge her with the control apparatus and circuits for controlling switch W are not illustrated since the specific form of such apparatus and circuits forms 5 no part of my present invention and hence have been omitted in order to avoid unduly complicating the drawings by circuits and apparatus well known to the art.

An approach relay AR is provided to control electric lock magnet M and an approach indicator AK. Relay AR is controlled by a circuit which will be pointed out in detail hereinafter.

The rails of section EF are supplied adjacent end F with current having distinctive characteristics and coded at one code rate or another according to the position of unit Ul of signal SF. The coding of this current is effected by means of a suitable code transmitter or coder CTF having a plurality of contact members each operated by the coder at a different code rate. For example, coder CTF is represented as being provided with contact members and I80 operated respectively by the coder at a rate of 75 and 180 times per minute. When unit UI is at stop, as indicated in the drawings, alternating current of a particular frequency coded at the 75 code rate is supplied to section EF at its exit end F over a circuit which extends from one terminal of secondary winding 23 ofline transformer LTF through condenser 24, contact 15 of coder CTF, contact l4l3 of controller J I operated by unit Ul of signal SF, and primary winding 25 of track transformer 'ITF to the other terminal of winding 23 through a common connection indicated by the reference character CC. Secondary winding 26 of track transformer TTF is connected to the rails of section EF adjacent its exit end F, and primary winding 22 of line transformer LTF is connected as by wires 21 and 28 to a suitable source of alternating current, such as a generator, not shown, supplying line wires 21 and 28 with current having a particular frequency of, say, 100 cycles per second, and it follows, therefore, that the rails of section EF are normally supplied at end F with 100 cycle current coded at the '75 code rate. When signal unit Ul is in either its caution or its clear position, contact l3--l4 of controller J l is opened and contact l3-l5 of controller J I is closed to connect secondary winding 23 of transformer L'I'l to transformer TTF through contact I80 of coder CTF so that 100 cycle current coded at the 180 code rate is supplied to the rails of section EF. The condenser 24 preferably is utilized to tune the circuit connection of transformer LTF to transformer TTF to effective resonance at the frequency of 100 cycles per second.

Relay TRE is connected to the rails at the entrance end E of section E--F through a transformer RTE which has its primary winding 30 connected to the track rails and has its secondary winding 3! connected through a condenser 33 and a rectifier 32 to the winding of relay TRE. The capacity of condenser 33 is selected with respect to the constants of the winding of relay TRE and secondary 3| of transformer RTE in such manner that the connection of the relay to the transformer is tuned to effective resonance only at the frequency corresponding to the frequency of current supplied to the rails at the opposite end E of the section, hence relay TRE is effectively energized and responds only to the 100 cycle current supplied to section EF at its exit end F.

Two decoding relays, designated by the refer ence characters HE and AJ E, are associated with and are controlled by relay TRE through the medium of a decoding transformer DTE and a decoding unit DUIBU. The decoding transformer comprises a secondary winding 35 inductively coupled with a primary winding 34, a portion of which is connected through a center-tapped connection to one terminal C of a suitable source of unidirectional current, such as a battery not shown but having its opposite terminals designated by the reference characters B and C, and the opposite ends of such portion are connected alternately to the other terminal B of this source according as relay TRE is picked up to close its front contact 36 or is released to close its back contact 31. It is readily apparent that when relay TRE follows code, primary winding 34 of transformer DTE is supplied with unidirectional current in such manner as to cause an alternating current having a frequency corresponding to the code rate of operation of relay TRE to be induced in secondary winding 35. This secondary winding is connected through a mid terminal connection to one terminal of relay HE and has its opposite ends connected alternately to the other terminal of relay HE according as relay TRE operates its contact members to close its front contact 38 or its back contact 39, respectively, and it follows that when relay TRE operates, the alternating current caused to be induced in winding 35 is supplied to relay HE as substantially unidirectional current. Relay HE is proportioned to be picked up when relay TRE responds to current coded at either the '75 or the 180 code rate received from the rails of section EF.

Relay AJE is connected to primary winding 34 of transformer DTE through decoding unit DUIBO, the details of construction of which are not shown in the drawings but which usually comprises a rectifier and a reactor condenser tuning unit tuned to resonance at a frequency corresponding to the 180 code rate whereby relay AJE is effectively energized and picked up when and only when relay TRE responds to 180 code received from the rails of section EF.

Relays HE and AJE cooperate in the usual manner to control signal SE by circuits which have been omitted from the drawings since they are well known. It is deemed sufficient to state that when relays HE and AJE are both picked up, signal SE is caused to display its clear indication; when relay AJ E is released and relay HE is picked up, signal SE is caused to display its caution indication; and when both relays HE and AJE are released, signal SE is caused to display its stop indication.

When section DE is unoccupied so that relay TRD is picked up, the rails of section EF are supplied at the entrance end E with current having characteristics distinctively different from the characteristics of the current supplied to the opposite end of the section. Such differently characterized current supplied at E to section EF may comprise, for example, alternating current having a frequency distinctively different from the frequency of the current supplied at the opposite end F of the section, and having a code rate determined according to the position of signal SE and the occupancy of section DE. Current of a frequency distinctively different from the cycle current supplied to end F of section EF, may be obtained from any suitable source, such as a generator of current having a distinctive frequency different from the 100 cycle current, or as shown may be obtained from a frequency changer FC comprising a transformer FT having a secondary winding 42 inductively coupled with a primary winding 4| supplied through a full wave rectifier 4!] with alternating current from the secondary winding 23 of a line transformer LTE. The primary winding 22 of transformer LTE is connected to a suitable source'of alternating current, such as line wires 21 and 28, and it is readily apparent that rectifier 4|] when energized by 100 cycle current supplies to winding 4| of transformer FT two pulses of unidirectional current in each cycle of alternating current, hence there is induced in secondary winding 42 of transformer FT by these double frequency pulses of unidirectional current in Winding 4|, an alternating electromotive force having a frequency which is double the frequency of the 100 cycie current supplied to rectifier 40. It follows, therefore, that secondary winding 42 of transformer FI may be considered as a source of alternating current having a frequency of 200 cycles per second, or a frequency distinctively different from the frequency of the 100 cycle current supplied at end F to section E-F.

When signal SE is in either its stop or its caution position and section D-E is unoccupied, contact l$ili of the associated circuit controller J3 is closed and 200 cycle current coded at the 180 code rate is supplied at end E to the rails of section E'F over a circuit extendin from one terminal of Winding 42 of transformer FT through condenser 43, front contact 44 of relay TRD, contact Itil of a code transmitter CTE, contact l'l-IG of controller J3, primary winding 25 of transformer ITE which has its secondary winding 26 connected to the rails at entrance and E of section E-F, and a common connection, indicated by the reference character CC, to the other terminal of winding i2. When section DE is unoccupied and signal SE is in its clear position so that contact iii-48 of controller J3 is closed, 200 cycle current coded at the 75 code rate is supplied to section EF at end E over a circuit which corresponds to the circuit over which 200 cycle current coded at 180 code is supplied to transformer TTE, except that contact iii-4B of controller J3 and contact T5 of coder CTE replace contacts lt-i'i of controller J3 and contact Hill of coder CTE, respectively. Coder CTE as shown is provided with a contact 20operated at a rate of 20 times per minute, and when relay TRD is released due to a train in section DE, 200 cycle current coded at the 20 code rate is supplied to transformer TTE over a circuit including back contact 38 of relay TRD and contact 29 of coder CTE, as is readily apparent from an inspection of the drawings. Condenser 63 is provided in the circuit connec tion of transformer FT to transformer TTE to tune the circuit connection to effective resonance at the frequency of 200 cycles per second.

Relay TRF is connected to the rails at exit end F of section EF through a receiving transformer RTF which has its primary winding 3!! connected to the rails of section EF and has a secondary winding 3| connected. through a condenser 53 and a rectifier 32 to relay TRF. Condenser 50 is selected with respect to the constants of the winding of relay TRF and winding 3| of transformer R'I'F so as to tune the circuit connection of the relay and transformer to effective resonance at a frequency corresponding to the frequency of the current supplied to the rails at the opposite end E of the section, and relay TRF accordingly is effectively energized in response only to the 200 cycle current supplied at entrance end E of the section.

Decoding relays HF and AJF are associated with and are controlled by relay TRF through a decoding transformer DTF in a manner substantially corresponding to the manner explained in detail heretofore whereby relays HE and AJE are controlled by relay TRE. In addition, transformer DTF has associated therewith another or slow code detecting relay BSA and a relay FSA. Relay FSA is arranged with its winding interposed in the circuit connection of front contact 36 of relay TRF to a portion of primary winding 34 of transformer DTF, and relay FSA when. en-

ergized closes its front contact 5| to complete an obvious circuit including relay BSA and over which another portion of winding 34 of transformer DTF is energized when back contact 31 of relay TRF is closed. The relays FSA and BSA are preferably sufficiently slow releasing to bridge respectively the off and. on intervals of 20 code energy, hence when relay TRF operates at the 20 code rate, relay FSA is energized each time relay TRF closes its front contact 36 in response to an on interval of. code energy received from the rails of the section, and with front contact 5| of relay FSA closed, relay BSA is energized each time relay TRF closes its back contact 31 in response to an off interval of code in the associated section. When, however, relay TRF is steadily energized, relay BSA is released since its energizing circuit is then held open at back contact 31 of relay 'I'RF, or if relay TRF is steadily released, both relays FSA and BSA are released since relay FSA is deenergized when its energizing circuit is held open at front contact 36 of relay TRF and with contact 5| of relay FSA open, relay BSA is likewise deenergized. It follows, therefore, that relay BSA is energized when and only when its associated. track relay 'I'RF operates in response to coded energy received from its associated section, and by properly proportioning the release period of relays FSA and BSA, relay BSA may be employed to detect operation of its associated track relay TRF in response to energy coded at the rate of 20 or more code cycles per minute. Relay BSA, as will be made clear presently, controls the approach lighting of lamp L! and L2 of signal SF, by at times energizing the lamps over an obvious circuit including back contact 52 of relay BSA.

When relay TRF' responds to either '75 or code current from section EF, relay HF is effectively energized and picked up to close its front contact 53 and thereby complete an obvious circuit for approach relay AR. Relay AR con trols an approach indicator AK over its front contact 54.

When relay TRF responds to 180 code from section E-F and units UI and U2 of signal SF are both at stop so that contacts ll-l2 of circuit controllers J I and J 2 are respectively closed, magnet M of the electric locking apparatus of lever V is energized over a normal circuit extending from terminal B through front contact 53.0f, relay HF, front contact 56 of relay AJF. contact lI-l2 of controller J2, contact Il|2 of controller J I, front contact 51 of relay AR, and the winding of magnet M to termina1 C. If relay AR is released, magnet M may be energized over either of two alternate circuits, one of which I shall term a track circuit release circuit which is completed when relay TRG is released and extends from terminal B through back contact 59 of relay 'IRG, contacts lll2 of controllers J2 and J l, respectively, back contact 60 of relay TRG and the winding of magnet M to terminal C; and the other alternate circuit I shall term a time release circuit completed at the end of a predetermined time delay required to operate to a closed position contacts SI and B2 of a time release device TD, which may, for example, be a time element relay, or as shown, a manually operated time release. This time release circuit extends from terminal B through contact 6| of time release device TD, contacts H--l2 of c0ntrollers J2 and J I, respectively, contact 62 of time release device TD and the winding of magnet M to terminal C.

As indicated in the drawings, unit Ul of signal SF is provided with an energizing circuit controlled by traffic conditions in the stretch (this control being indicated conventionally by the representation of traffic controlled contact 65), and including contact 66 of lever V closed in the reverse position of the lever and contact 61 closed in the normal position of time release TD.

The apparatus of Fig. 1 is in its normal condition, as represented in Fig. 1, when sections D-E, E-F and F-G are unoccupied, and units UI and U2 of signal SF are at stop. In this condition of the apparatus, 100 cycle current coded at the '75 code rate is supplied to the rails of section EF at its exit end F in a manner previously described, and relay TRE responds to such current to hold relay HE energized and relay AJE released so that signal SE is in its caution position. With signal SE at caution, 200 cycle current coded at the 180 code rate is supplied to the rails of section EF at entrance end E, as previously mentioned, and relay TRF in response to such current holds relays BSA, FSA, HF and AJF energized. Approach relay AR accordingly is energized, approach indicator AK is illuminated, and lock magnet M of lever V also is energized.

When lever V is operated to clear unit Ul of signal SF, contacts ll-I2 and I3-l4 of controller Jl are opened in response to the clearing of unit Ul. The previously traced normal circuit of lock magnet M is opened when contact l ll2 of controller J l opens, and as a result magnet M releases to render effective the electric locking of lever V. When unit Ul clears, contact I3|5 of controller J l is also caused to close and shift the coding of the 100 cycle current from the 75 code rate to the 180 code rate, as explained previously. Relay TRE accordingly causes both relays HE and AJE to be energized in response to the 180 code rate received from the rails of section EF, and signal SE is controlled to its clear position, thereby causing controller J3 to open contact Iii-11 and close contact |6|8 so that the coding of the 200 cycle current supplied to section EF at E is shifted from the 180 code rate to the '75 code rate. At the opposite end of section EF, relay TRF responds to the 200 cycle current coded at the '75 code rate, and relays HF, FSA and BSA are energized but relay AJF is released.

If, now, the operator moves lever V towards its normal position prior to a train entering section D-E, unit U! of signal SF is restored to its stop position, but the lever is prevented by the electric locking from occupying its full normal position N at this time so that operation of switch W cannot be effected. However, when unit Ul goes to stop, contact ll-l2 of controller J l closes to shift the coding of the 100 cycle current supplied at end F of section EF from the 180 code rate tothe '75 code rate, and relay AJE at entrance end E of the section accordingly drops in response to relay TRE following the 100 cycle current coded at the 75 code rate, Signal SE accordingly is operated to its caution position, and contact l6l1 of controller J3 closes so that the 2.00 cycle current supplied to end E of section EF is coded at the 180 code rate. This 200 cycle 180 code current causes relay TRF to operate and energize all the associated decoding relays AJF, HF,FSA and BSA, and electric lock magnet M accordingly becomes energized over its previously traced normal circuit to actuate locking dog 2| from engagement with locking segment I 9, thereby permitting lever V to be restored to its full normal position N and conditioning the apparatus to permit an operation of switch W. It is to be noted that lock magnet M is energized to release the locking of lever V, only if signal SE goes to caution to alter the code rate of a 200 cycle current from the 75 to the 180 code rate. The releasing of the locking of lever V indicates that distant signal SE is displaying the proper restrictive indication, and it follows that the apparatus of Fig. 1 effects signal indication locking wherein the proper restrictive indication of a distant signal is checked prior to releasing the locking of the control lever of the associated home signal.

If, with lever V in its reverse position R to clear unit Ul of signal SF, and with signal SE cleared so that 200 cycle current coded at the 75 code rate is supplied to' the rails of section EF with the result that relays HF, FSA and BSA are energized but relay AJF is released and lock magnet M also is released, atrain enters approach section DE, the releasing of the associated track relay TRD prevents a release of the electric locking over its normal circuit in the manner above described, and the rails at the entrance end E of section EF are supplied with 200 cycle current coded at the 20 code rate over a circuit previously traced and including back contact 48 of relay TRD and contact 20 of coder CTE. Relay HF accordingly releases due to relay TRF following the 20 code 200 cycle current. with the result that approach relay AR also releases to interrupt the energi'zation of indicator AK. Indicator'AK thereupon becomes dark to indicate that a train is approaching signal SF within the limits of sections D-E and EF. Relays FSA and BSA, however, remain energized and the signal lamps of signal SF remain dark.

In the event that, with the apparatus'in the condition just described, lever V is operated toward its normal position N, unit Ul of signal SF goes to stop but the lever is prevented by locking dog 2! engaging segment I9 from occupying its full normal position. When unit Ul goes to stop, the cycle current supplied to section E-F is shifted from the to the 75 code rate, and signal SE accordingly is controlled to its caution position. With relay TRD released, however, the code rate of the 200 cycle current supplied to section EF is not affected by the change in position of signal SE, so that relays AJF and HF remain released to retain approach relay AR and lock magnet M released. Lever V accordingly remains locked out of its normal position N, but may be restored to its normal position by operating the time release deviceTD. At the end of the predetermined time interval of this release,

contacts 6| and 62 become closed to complete the previously mentioned time release circuit for lock magnet M, which circuit includes contacts 6! and 62 and contacts ll-I2 of controllers J I and J2, respectively. Magnet M accordingly becomes energized to actuate locking dog 2| and unlock the lever to permit it to be operated to its full normal position, and it follows, therefore, that when a train occupies an approach section, a time release of the locking of lever'V may be effected at the expiration of a predetermined time delay enforced by a time release device.

When a train occupies section E-F, both relays TRE and TRF are shunted and all decoding relays associated therewith are released. Signal SE is controlled to its stop position, while the lamps L! and L2 of signal SF are illuminated due to relay BSA closing its back contact 52. The lamps of signal SF accordingly are approach energized by the apparatus of Fig. 1 when a train occupies section EF.

With the train in section EF, it is, of course, obvious that with lever V in its reverse position and unit Ul of signal SF cleared, the operator may restore signal SF to its stop position and may restore lever V to its full normal position by moving lever V toward its normal position and by operating the time release device TD. At the end of the predetermined time interval of release TD, magnet M becomes energized to unlock lever V in the manner pointed out in detail heretofore.

In the event, however, that signal SF is cleared and the train accepts the clear indication and enters section F-G, relay TRG is shunted and releases to set unit Ul of signal SF to stop and to effect a track circuit release of the locking of lever V over a circuit previously traced and including back contacts 59 and 60 of relay TRG and contacts |l-l2 of controllers J l and J2, respectively. The operator may now restore lever V to its full normal position N and it follows that the locking of lever V is automatically released when the train enters the section governed by the signal controlled by such lever.

Signal SE goes to caution when the train vacates section EF since the 100 cycle current supplied to section EF at end F is coded at the 75 code rate When unit Ul is at stop, hence relay TRE operates to energize decoding relay HE but not AJE. The apparatus of Fig. l of course is restored to normal when the train vacates section F-G and relay TRE picks up.

From the foregoing description, it is readily apparent that the apparatus embodying my invention provides means whereby control of one function and approach locking of another remotely located function, are effected by utilizing the track rails as transmission conductors, thereby obviating the necessity of pole line or auxiliary wires along the track. Also, it is apparent that such control and approach locking of these remotely spaced functions are incorporated into a system which also provides approach control of one of the functions and signal indication locking of the other function.

Figs. 2a and 2b, when placed end to end with Fig. 260 on the left, represent a system which I shall refer to hereinafter as being shown in Fig. 2, wherein the apparatus of Fig. l is represented modified to provide traflic locking between two control points or towers P and Q at opposite ends of a stretch of single track X connected at its right-hand end, as viewed in the drawings, by switch WI to a siding track Y and connected at its left-hand end by switch W2 to a siding track Z. The rails I and Id of track X are divided by insulated joints 2 to form a track section EF extending from adjacent tower P to adjacent tower Q, while detector track sections DE and F-G are provided for switches W2 and WI, respectively, by lnterposing, insulated joints 2 in rails I and la at the opposite ends of stretch X.

Section EF is provided with a track circuit which substantially corresponds to the track circult of section EF of Fig. 1, and which differs from the track circuit of section EF of Fig. 1 in that relay TRE of Fig. 2a is conditioned to respond to either 200 or 100' cycle current according as a traflic lever V8, to be referred to later, is in its respective normal or reverse position, and relay TRF of Fig. 2b is similarly conditioned to respond to either or 200 cycle current according as another traflic lever V3 is in its normal or reverse position. The detector sections DE and F--G are also provided with track circuits, which include relays TRD and TRG, respectively. These track circuits have been represented for simplicity as being of the usual type comprising a source of current at one end and a track relay at the opposite end, but it is to be understood, of course, that such circuits may be arranged in a manner corresponding to that of section EF, and which arrangement, as will be made clear presently, is particularly effective for controlling apparatus on a train irrespective of the direction of the train movement.

Each end of section EF is provided with a source of 100 cycle current and a source of 200 cycle current. The 100 cycle current may be derived from line wires 21 and 28, and the 200 cycle current may be derived from frequency changers FC corresponding in construction to the frequency changer FC illustrated and described in connection with the apparatus of Fig. 1.

Eastbound traflic operating over track X from left to right as viewed in the drawings is controlled by a distant signal ESE disposed adjacent end E and by a home signal ESF at end F of section EF. Westbound traffic on track X is governed by a distant signal WSF at end F and a home signal WSE at end E of section EF. The distant signals ESE and WSF, and home signals ESP and WSE, preferably correspond respectively to the distant and home signals SE and SF shown in Fig. l and described heretofore; and each signal unit shown in Fig. 2 is preferably provided with a circuit controller designated by the reference character J with a suitably distinguishing sufiix.

Home signals ESF and WSE are semi-automatic signals controlled by trafiic conditions on track X and by control levers VI and V6, respectively, in a manner corresponding to that mentioned heretoforewhereby signal SF is controlled by the apparatus of Fig. 1. Distant signal WSF at F is controlled by the track circuit apparatus of section EF and by a signal control lever V2, while distant signal ESE at E is controlled by the track circuit apparatus of section EF and by a signal control lever V5, as will be made clear presently.

Signal control levers VI and V2 are incorporated into interlocking apparatus located at tower Q and have associated therewith traffic levers V3 and V4, while signal control levers V5 and V6 are incorporated into interlocking apparatus at tower P and hav associated therewith traflic levers V"! and V8. In accordance with the usual practice, the interlocking apparatus at tower Q is provided with locking means arranged as indicated by the chart represented in Fig. 2b in such a manner that when lever V2 is in its reverse position R, lever V3 is locked in its normal position N and lever V4 is locked in its reverse position R, and when lever V3 is in its reverse position R, lever V4 is locked in its normal position N. In like manner, the interlocking apparatus at tower P'is arranged as indicated by a chart represented in Fig. 2a in such manner that when lever V6 is in its reverse position R, lever V1 is locked in its normal position N and lever V8 is locked in its reverse position R, while" contacts selectivelyclosed in accordance with the position occupied by the lever, and each con tact of the lever .loearsthe reference character N.,or R to designate-the position of the associated lever in. which such contact is closed.---For convenience intracing circuits, the contacts of the levers have been represented in the drawings re' mote from the leverscontrolling such contacts, but each of such contacts has been designated by the reference character of the associated control lever, by a reference character individualto such contact, .and'by'the reference-character N or .R to indicate the position of the associated lever at which the contact is closed. For example, lever contact85'bearsthereference characters N and V8. to. indicate that this contact is controlled by lever V8 and is closed only when such leveris in itsnormal position N,- while lever contact 86 bears the reference characters R and V8 to indicate that this contact is closed -o'nly when lever V8 is in its reverse position R.

. Similarly, to facilitate tracing circuits, contacts of certain relaysarerepresented in Figs. 2a and 2b. disposed remotefrom the relays operating such 'cont-acts but each of such contacts has been represented .in itsnormal position and bears the reference character of theassociated relay oper ating such contact as well as a reference character individual to such contact. Thus, back contact .59 bearsv the reference character TRG and .is representedin its'open position to indicate that such contact is controlled by relay TRG and is normally open.

.The coders CTE and CTF of Fig. 2 aresimilar to coders CTE and CTF of Fig. 1,-except that-in Fig. 2 coder CTF is provided with an additional coding member Zdoperated at a rate of 20 times per-minute, and'coder CTE is provided with an additional coding memberlZD operated at'th'e rate-of 120 times-per minute. Coder C'I'E has associated therewith additional coding apparatus capable of providing relatively low code rates of the order of 20, 1'7 and 15 cycles per second. Such additional coding apparatus may comprise a motor operated device having a plurality of contactmembers operated respectively at the several relatively low code rates, or as shown may comprise a plurality 'ofi code generating and code disconnecting relays, designated respectivelyby the reference characters CG and CD with suitis' non-responsive to-operation of the associated relay TRF unless either lever V-l or V3 is in its reverse position. I y

I *Thedecoding apparatus associated with relay TRF additionally includes other decoding means responsive to the previously mentioned relatively low code ratesofthe order of 20, 17 and cycles per minute. Such additional decoding ap-' nated by the reference-character CR with a suit-- ably distinguishing prefix. The arrangement and manner ofoperation' or the additional decoding apparatus associated with relay TRF will be explained in detail presently; but at this-time it should be pointedout that such apparatusis conditioned to be active only when both traffic levers V3 "and V4 occupy thennormal positions so that contacts 82 and 33 of levers and V4, -respectively, are closed. Itshould also be noted that both the-code registeringrelays' CR and the decoding relays associated with the "decoding transformer DTF, are efiective to control lock magnet M! of lever V I, and the approach relay ARI, in a mannersubstantially corresponding to the manner that' rnagne't M and relay AR are controlled by nieapparatus-or Fig. 1. r a *1 hssociated with the decoding apparatus of relays 'I'RE and TRF are two indicators, desig hated respectively by the reference characters K ancvK with distinguishing sufiixes corresponding to-jth'e -suffiX of; the associated track relay; IllannlfOf control and the function of such cators wiil be 'pointed'out "hereinafter. 1 Each control station ortoweris additionally provided with a'manually operable circuit controller, such as a push button FBI or P132 shown provided fo'r stations" Q'or P, as the case may be. The functions-of thesepush buttons will be explained hereinafter.

'Th'eapparatus represented in Fig. 2' is in its normal condition; as represented in the drawings,

ably distinguishing suffixes, arranged in amanner explained hereinafter tointerrupt or code current in'a, circuit at a rate of 20, 17 or 15 minute. The decoding apparatus associated with relays TREand. TRF of Figs. 2a and 22) substantially times per correspond to the similarapparatus shown provided for relaysv TRF .and TRE, respectively, of

Fig. 1, except that in Fig. 2 the decoding appa ratus associated; with relay TRF incorporates an .76 additional decoding ,relay,.designated by the ref erence characterBJF', connected through a de V when sections DE, EF and FG are unoccupied; levers V all occupy their normal positions, andall signals a're at stop. In this normal condition ofthe apparatus, contact 85 of 'lever*V 8 is closed so that relay TRE i'sconditioned by condenser 50 to respond to 200 cycle currentgwhile contact! of lever V3 is closed andas-a result relay TRF is conditioned by condenser 33 to-respond' to cycle current. Current having a frequency of 200 cycles and a code rate of is supplied to the railsof section E'-'F at end F over a circuit extending from one terminal of secondary winding 42 of transformer FT of frequencychanger FC through condenser 43,"normal contact 89 of lever V3, normally-closed contact!!! of push button PBl, contact I80 of coder 'cTF, contact fil -I8 of circuit controller J 3F operated by signal WSF, front contact 92 of relay TRG,-norma1 contact 93 of lever V3, primary winding 25 of .track transformer T'II and through a common connection, indicated by the reference character CC, to the other terminal of winding 42. Relay TRE operates in response to this current and all decoding relays associated therewith are energized, as represented in Fig. 2a. Approach relay ,ARZ, indicator AKE,, and lock magnet M2 associated with lever V5 at tower P accordingly are energized, as is readily apparent from an inspectionof the drawings, but indicators KE and VKE are deenergized.

At end E of section EF', 100 cycle current coded at the relatively low code rates ofe20 and 17 cycles per minute successively, is supplied to the rails of section E-F over a circuit extending from one terminal of secondary-winding ,23 of line transformer LTE through condenser 24, l

back contacts 95, 96 and 91 of code generating relays CG20, CGI'I and CGI5, respectively, normal contacts 98 and 99 of levers V1 and V8, respectively, and primary winding 25 of track transformer TTE through a common connection indicated by the reference character CC to the other terminal of winding 23. This coding of the 100 cycle current is effected by the code generating relays CG in the following manner.

Referring to Fig. 2a,- the code generating relays CG are shown all ,deenergized, and the, cirsuit for. a first slow release code generating relay CG20 is represented completed and extends from terminal B through normal contacts I and IOI of levers'VI and V8, respectively, front contact I02 of relay TRD, back contact I03 of code disconnecting relay CD20, the winding of relay CG20, 'back contact I04 of relay CDI'I, back contact I05 of relay CGI'I, back contact I06 of relay CDI5 and back contact I01 of relay CGI5 to terminal C. Relay CG20 accordingly picks up to open its back contact 95 interposed in the circuit over which 100 cycle current is supplied to transformer TTE, thereby interrupting or coding such current, and relay CG20 also closes its front contact I08 to complete an obvious circuit for relay CDZO. Relay CDZIlpicks up at the end of its slow pick-up period, closing its front con tacts I09 and II0 but opening its back contact I03 to deenergize relay CG20, which latter relay drops at the end of its slow release period. To accord with the heretofore assumed code of 20 cycles per minute, the slow acting periods of relays CG20 and CD20 are selected so that the slow pick-up period of relay CD20 and the slow release period of relay CG20 together approximate 3 seconds, hence it follows that relay CG20 when energized remains picked up to hold open for approximately 3 seconds the circuit supplying 100 cycle current to transformer TTE. When relay CG20 drops, its back contact 95 closes to complete the circuit over which trans former TTE is supplied with current. Back contact III of relay CGZO also closes to complete a circuit for relay CGII extending from terminal B through back contact III of relay CG20, front contact I09 of relay CD20 (held closed during the slow release interval of this relay), contact II2 II3 of circuit controller J3E operated by signal ESE, back contact II5 of relay CDI'I, the Winding of relay CGI'I, back contact I06 of relay CDI 5 and back contact I01 of relay CGI5 to terminal C. 7 Relay CGI'I thereupon picks ,up to open its back contact 96 and interrupt or code the current supplied to transformer TTE, and front contact llfi closes to complete an obvious circuit for relay CDII. Relay CD I'I picks up at the end of its slow pick-up period, opening its back contact 5 to interrupt the energization of relay CG", and closing its front contact II] to complete for relay CD20 a stickcircuit extending from ter, minalB through front contact I I6 of relay CGI I, front contact II! of relay CDI'I, contact II8 I I9 of controller J 3E operated by signal- ESE, and front contact H0 and the winding of relay CD20 to terminal C. At the end of its slow release period, relay CGII releases to close its back contact 96 and thus completethe circuit of transformer TTE which accordingly becomes energized. The slow acting characteristics of relays CGIl and CDI'I are selected so that the slow pick-up period of relay CDI 'I and .the slow release interval of relay CGII when added together approximate 3'.5 seconds.

When relay CGI'I drops, its front contact II6 opens toopen the previously mentioned energizing circuits of relays CD20 and CDI'I, and at the expiration of their slow release periods, these relays drop to restore the additional coding apparatus to the condition illustrated in the drawin whereupon the apparatus starts another cycle of coding due to the energization of relay CG20. This operation of the relays continues as long as levers V1 and V8 are in their respective normal positions, relay .TRDis energized, signal ESE is at stop, and push button PB2 is unactuated.

It is readily apparent, therefore, that when the additional coding apparatus operates in the mannerjust described, the circuit of transformer TTE is opened for approximately 3 seconds when relay CG20 is picked up, is momentarily closed when relay CG20 drops, is open for approximately 3.5

seconds when relay CGI'I is picked up, and is closed until relays CD20 and CDI1 drop at the end of their slow release intervals to restore the apparatus to normal and enable relay CG20 to pick up and initiate another cycle of coding. Under such conditions transformer TTE is supplied with a first pulse of current followed by a 3 second interval when no current flows, and a second pulse of current followed by 3 /2 second interval when no current flows, and this coding of the current is cyclically repeated. I shall term this type of coding as comprising a combination 2.0,1'7 cycle code, in that the coding includes pulses of current which occur at 3 second intervals (or 20 pulses per minute) and pulses of current which occur at 3.5 second intervals (or approximately 17 pulses per minute).

From an inspection of the drawings, it is readily apparent that if push button PB2 is actuated when levers V1 and V8 are in their normal positions, relay TRD is energized and signal ESE is at stop to close contacts I I2I I3 and I I8-I I9, then the current supplied to transformer TTE is coded ata combination code comprising successive intervals of 20, 17 and code rates. This coding occurs since with pushbutton PB2 actuated to close contact I23, relay CGI5 becomes energized when relay CGI'I drops, and relay CGI5 accordingly picks up to energize relay CDI5 and hold relays CDI'I and CD20 energized Relay CGI5 picks up when relay CGI'I drops, over a circuit extending from terminal B through back contact I24 of relay CGIl, front contact I25of relay CDI'I, contactl23 of push button PB2, back contact; I26 of relay CDI5, and the winding of relay CGI5; to terminal C. Relay-CGI5 in picking up opens its back contact 91 to open the circuit Over; which current is supplied to transformer T'IE,'an d also closes its front contact I21 to energize relay CDI5. Relay CDI thereupon picks up at the end of its slow pick-up period to close its front contact I28, whereupon relay CDII becomes energized over a stick circuit extending from terminal B through front contact I27 of relay CGI5, front contact I28 of relay CDI5, front contact I29 of relay CDII and the winding of relay CDI'I to terminal C. Relay CD20 also becomes energized over a stick circuit connected in multiple with relay CDII and extending from contact I29 of relay CDI'I through contact I I7 of relay CDI I, contact II8II9 of circuit controller J 3E, and front contact I II! and the Winding of relay CD2 9 to terminal C. The energization of relay CGI5, however, is interrupted at back contact I23 of relay CDIE when the latter relay picks up, and relay CGI 5 drops at the end of its slow release interval to close its back contact 9! and thereby complete the previously traced circuit of transformer TTE. The slow acting characteristics of relays CGI5 and CDI5 are selected so that the slow pick-up period of relay CDI5 when added to the slow release period of relay CG! 5 approximates 4 seconds. It is readily apparent, therefore, that when relay CGI5 is picked up, the circuit of transformer 'IIE is held open for 4 seconds. When relay CGI5 drops at the end of its slow release interval, relays CD! 5, CDI I and CDZIJ all become deenergized and these relays release at the end of their respective slow release intervals to condition the apparatus to reenergize relay CGZfi and initiate another cycle of operation of the coding apparatus. It follows, therefore, that if push button PB2 is held down when signal ESE is at stop and relay TRD is energized, transformer TTE is supplied with a first pulse of current followed by a 3 second off interval when relay CGZB is picked up, a second pulse of current followed by a 3 /2 second off interval when relay CGIl is picked up, and a third pulse of current followed by a 4 second off interval when relay CGI5 is picked up; and that this coding of current which I shall term a combination code of 20, 17 and cycles, is cyclically repeated.

Other codes and combinations of codes are provided by the coding apparatus above described, as is readily apparent from an inspection of the drawings. For example, with relay TRD picked u and signal ESE at its clear position to open contact I I2-I I3 and close contact I I2I I4, the current supplied to transformer TTE is coded at the code rate only if push button PB2 is unactuated, or at a combination of the 20 and 15 code rates. if push button PB2 is actuated to close contact I23. Similarly, if relay TRD is released and signal ESE is at its stop position to close contact I III-I I3, current supplied to transformer 'I'TE is coded at only the 17 code rate if push button PB2 is unactuated, or at a combination of the 17 and 15 code rates if push button PB2 is actuated to close contact I23. 0n the other hand, with signal ESE cleared to close contact II2I I4 and with relay TRD released,

current coded at the 15 code rate only will be supplied to transformer TTE if push button PB2 is actuated to close contact I23. It follows, therefore, that when relay TRD is picked up, the current supplied to transformer TTE Will be coded at the 20 code rate or at a combination code inclifdfigthe 20 code rate; if signal ESE is at stop to close contact I I2-I I3, the current will be coded at the 17 code rate or at a-combination code including the 17 code rate; while if push button PB2 is actuated to close contact I23 the coding of the current will include the 15 code rate.

These relatively low rates of coding the current supplied at end E of section EF are detected at the other end of the section by the code selecting relays CS and code registering relays CR. When the apparatus is in its normal condition as illustrated in Fig. 2 wherein cycle current coded at a combination code of 28 and 17 code rates is supplied to section EF at end E, relay TRF responds to each pulse of current by picking up during the interval such current flows and releasing when the current flow ceases. For example, when relay TRF responds to a combined 20-17 code, it is energized when the code generating relays CG are released to complete the circuit of transformer TTE, and front contact I32 of relay TRF closes to complete for relay 2003 an engizing circuit extending from terminal B through normal contacts 82' and 83 of levers V3 and V4, respectively, front contact I32 of relay TRF, back contact I33 of relay CIR and the winding ofrelay 2008 to terminal C. Relay 200s accordingly picks up to close its front contact I 34 and connect the winding of relay CIR in multiple with the winding of relay 20CS. Relay CIR is slow in picking up, while relay ZOCS is slow in releasing, the slow acting characteristics of these relays being selected in such man'- ner that the slow release period of relay 2008 and the slow pick-up period of relay CIR add up to approximately 3 seconds. When relay CIR picks up at the end of its slow pick-up period to open its back contact. I33, relay ZOCS is deenergized but remains picked up due to its slow release characteristics.

With relay ZUCS picked up, relays I 'I'CS, ISCS and I3CS also are picked up in sequence over front contacts I35, I36 and I31 of relays 200$, I'ICS and I5CS respectively. Each relay I'ICS, IECS and I3CS preferably is provided with slow releasing characteristics which hold each of such relays picked up for substantially /2 second after it is deenergized. v

At the end of the on period of current, that is, when code generating relay CGZG picks up, relays TRF and CIR release. During the 3 seconds off interval ofthe code that results due to the energization of relay C'GZG, relay ZIICS releases to open its front contact I34 and close its back contact I4I. Relay CGZG, however, releases to complete the circuit of transformer 'ITE prior to relay I'ICS releasing, so that when relay TRF picks up due to the on period of current following the 3 second o'ff interval, code registering relay 200R is energized over a circuit extending from terminal B through normal contacts :82 and 830i levers V3 and V4, respectively, front contact I32 of relay 'TR'F, back contact I33 of relay CIR, front contact I38 of relay I 30S, front contact I39 of relay IECS, front contact MILof relay IICS, back contact I4I of relay 2008 and the winding of relay ZIICR to terminal C. Also, relay 260s ispicked up to recomplete the circuit of relay CIR, and to cause relay CIR to be .reenergized and picked up. Relay ZIICR is deene'rgized When-relay ZBCS picks up to open its back Contact NI, but relay 200R remains up due to its slow releasing characteristics which are selectedto provide substantially a 12 second retardation of the release of the relay.

When code generating relay CG'II picks up, relays 'I'RF and CIR drop, and during the 3 /2 second interval that relay CGII is held up, relay '20CS fir'st drops followed by relay IICS at the end of its half-second release interval. Relay CGII, however, drops to complete the circuit of transformer TTE prior to relay ICS dropping at the end of its half-second release interval, so that when relay TRF picks up due to the on period of current following the 3 /2 second off period, code registering relay I'ICR picks up over a circuit substantially corresponding to the circuit previously traced for relay 20CR but in which front contact I40 of relay IICS is open so that relay 20CR is deenergized, and back contact I42 of relay N08 is closed so that relay I'ICR is energized.

Relay 2008 also picks up to energize relay CIR, and relay CIR in turn picks up to open the circuits of relays ZIlCS and I'ICR. Relay IICR remains up, however, since all detecting relays CR are provided with slow releasing periods of approximately 12 seconds, and relay 2008 also remains up due to its 3 second release interval. When the coding apparatus at end E of the section cyclically repeats the coding of current at the 20-17 code rate, relays 20CR and IICR are alternately energized when relay TRF responds to on periods of code separated by off periods having a duration alternately of 3 seconds and 3 /2 seconds, and these relays therefore indicate that relay TRF is responding to a composite code comprising the 20 and 17 code rates.

In the event that relay TRF responds to a code involving the 15 code rate wherein an on period is followed by an off period having a duration of four seconds, then relays ZIJCS, "CS and I5CS all release during the 4 second off interval, and during the next succeeding on period relay I5CR becomes energized over a circuit similar to the circuit previously mentioned for relay ZEICR but in which back contact I43 of relay I5CS is closed to connect the winding of relay I5CR to the circuit. The energization of relay I5CR indicates that relay TRF is responding to a code including the 15 code rate. It follows, therefore, that relays 200R, I'lCR and I5CR detect the different relatively low rates at which energy is coded by the code generating relays CG.

In a modified arrangement of the code detecting apparatus, shown in Fig. 3, the code registering relays CR are provided with slow releasing repeater relays CRP so arranged as to be selectively energized in accordance with the energization of the associated code registering relays. The slow releasing characteristics of the repeater relays are selected so that substantially a 12 second control interval may be provided for each code registering relay although such relays themselves have only, say, 6 second release intervals. To effect such 12 second control intervals, a plurality of slow releasing relays are employed one to detect each individual code rate of each combination of relatively low code rates. Referring to Fig. 3, the slow releasing repeater relay ICRP is provided with an energizing circuit extending from terminal B through front contact I50 of relay ZIlCR, front contact I5I of relay I'ICR and the winding of relay ICRP to terminal C, hence relay ICRP is energized whenever relays 20CR and IICR are picked up in response to a combination 20-17 code. Relay ICRP controls the control circuit governed by the associated code detecting relay ZIICR and, as indicated, has a front contact I52 which may be connected in an alternate circuit path around front contact I44 of relay 200R in the obvious energizing circuit of approach relay ARI of Fig.

21). Relay ZCRP is energized over a circuit extending from terminal B through front contact I53 of relay IICR, front contact I54 of relay 200R, and the winding of relay ZCRP to terminal C, and hence is energized when relays 200R and I'ICR respond to a combined 20 -17 code. Relay 2CRP controls a contact I55 which may be employed in aiding relay IICR in the control of associated apparatus, such as lock magnet MI of Fig. 2b. Relay 3CRP is provided with a circuit including front contacts I50 and I56 of relays 200R and I5CR, respectively, and thus detects a 20-15 code combination; relay 4CRP is picked up over a circuit including front contacts I51 and I58 of relays [5GB and ZIICR, respectively, and also detects a 20-15 code; relay 5CRP is energized over a circuit including front contacts I53 and I59 of relay I'ICR and I5CR, respectively, and thus detects a 17-l5 code combination; while relay GCRP is energized over front contacts I51 and I60 of relays I5CR and I'ICR, respectively, and also detects a 17-15 code combination. Each of these relays when energized controls contacts which may be interposed in the control circuits governed by relays I5CR,

I'ICR and 20GB, respectively, of Fig. 2b.

It follows that by providing relays CR with slow releasing repeater relays CRP, the slow releasing relays ZOCR, I'I'CR and I5CR might release due to relatively long intervals between successive pulses of the codes detected by such relays, without effecting the control established by such relays since the slow releasing repeater relays will remain up. In this manner, the slow release intervals of relays CR of Fig. 2b may be decreased.

As shown in Fig. 2, relays ZOCR and I'ICR are picked up to indicate that relay TRF is following cycle current coded at the combined 20 and 1'7 code rates. Approach relay ARI accordingly is energized over a circuit including front contact I44 of relay 200R, thereby causing approach indicator AKF to be illuminated, and lock magnet MI is energized over a circuit includin front contact I45 of relay I'ICR, contacts II-I2 of circuit controllers JZF and J IF, respectively, front contact 51 of approach relay ARI and the winding of magnet MI to terminal C. Indicator KF also is illuminated over a circuit including front contacts I41 and I46 of relays I'ICR and ZOCR, respectively.

If a train is to be moved on stretch X from tower Q to tower P, the operator at tower Q indicates the proposed traffic movement by depressing push button PBI, thereby changing the coding of the 200 cycle current supplied to the rails at end F of section EF from the to the 20 code rate. Relay TRE thereupon responds to this 20 coded current, and relays HE and AJ E drop, thereby deenergizing relay AR2, lever lock magnet M2, and indicator AKE. Indicator VKE also becomes energized over an obvious circuit including back contact I65 of relay HE and front contact I66 of relay BSA, thereby indicating that a west-bound train movement from tower Q to tower P is proposed.

If conditions at tower P are favorable for a. westbound movement, the operator at tower P may indicate such favorable conditions by depressing push button PBZ or by reversing lever V'I. For example, if push button P32 is depressed, the coding of the 100 cycle current supplied to section E-F is changed from the 20-17 combination code to a 20-17-15 code combination, as explained heretofore, and relay 'I'RF responds to this code to cause code detecting relays ZOCR, ITCR and ICR to be picked up. When relay I5CR picks up, its front contact 149 closes to complete an Obvious circuit for indication lamp VKF, which accordingly becomes illuminated to indicate that the operator at tower P consents to e westbound move. The operator at tower Q may now release push button PBI, thereby restoring the coding of the 200 cycle current to the 180 code rate, whereupon relays AJ E and HE at the other end of the section pick up and indication lamp VKE goes out.

The operator at tower Q may now operate westbound traffic lever V4 to its reverse position, thereby interrupting at contact 83 the supply of current to the supplemental decoding apparatus associated with relay TRF, and closing contact 8| to condition decoding transformer DTF to be energized and thus condition relays AJF, BJF and HF for operation. The operator at tower Q may also move signal lever V2 to its reverse position, thereby locking lever V4 in its reverse position. and lever V3 in its normal position. When indication lamp VKE at tower P becomes dark due to the release of push button PB! at tower Q, the operator at tower P may reverse westbound trafiic lever V1, thereby opening contact IOU to deenergize the code generating relays CG, opening contact 98' to disconnect the 100 cycle current from the track rails, and closing contact H58- to connect the 100 cycle current to the track rails of section EF over one contact or another of coder CTE. If, for example, conditions at tower P are such that signal WSE may be operated to clear or caution, the operator may move lever V5 to operate signal ESE from its stop position, and contact I3--l5 of controller J 5E operated by signal WSE closes to complete a circuit for transformer TTE, this circuit extending from one terminal of winding 23 of line transformer LTE through condenser 24,'lever contact I68 of lever V'l, contact I80 of coder CTE, contact I5l3 of circuit controller J IE, contacts I69 and I'll] of lever V'i, contact 99 of lever V8, winding 25 of transformer TTE and common connection CC to the other terminal of winding 23 of line transformer LTE. However, if the operator at tower P keeps signal WSEat stop, then contact l3--|4 of controller J IE is closed and the 75 code contact of coder CTE is effective to code the current supplied to transformer TTE, as is readily apparent from an inspection ofthe drawings.

Relay 'IRF responds to-this 100 cycle current and picks up relay HF, or relays HF and AJF,

according as the current is coded at the 75 or 180 code rates, and signal WSF accordingly is caused, with contact I14 of lever V2 closed, to display its caution indication if only relay HF is picked up due to relay TRF following '75 code, or its clear indication if both relays HF and AJF are picked up due to relay TRF following 180' code.

With signal WSF at eitherit's caution or clear condition, the apparatus is conditioned to permit a movement on track X from tower Q to tower P. When the train enters the limits of section F-G, relay TRG of course is released and drops to open its front contact 92 and thereby interrupt the circuit connection of the 200 cycle current source to the rails at end F of section EF. Relay TRE at theopposite end of the section accordingly becomes deenergized, and all decodingv relays associated therewith release so that approach relay ARZ, lock magnet M2 and i'ndication'lamp AKE also become deenergized,

and indication lamp KE becomes energized. If, now, lever V5 is in its reverse position, the approach locking of the lever is rendered effective since with magnet M2 deenergized, the lever can not be restored to it's full normal position unless the time release device 'IDE associated with lever V5 is actuated, as pointed out heretofore in connection with the operation of the apparatus of Fig. 1.

When the train occupies section E-F, signal WSF of course goes to stop since relay TRF is' shunted and the associated decoding relays are released. When the train occupies section D- E and shunts relay TRD, back contacts 59 and'SO of relay TRD close to complete the previously mentioned track circuit release circuit of relay AR2, thereby unlocking lever V5. Signal lever V2 may be restored to normal, and traflic levers V4 and V1 may also be restored to normal so that when the train vacates section EF, the apparatus is restored to its normal condition.

It is, of course, to be understood that modifications in the apparatus just described may be utilized to provide both indications and proposed traffic movements and traffic locking. For example, if indicator VKE at tower P becomes illuminated to indicate a proposed westbound train movement, the operator at tower P may respond by merely mov ng eastbound traffic lever V1 to its reverse position, thereby deene'rgizing at contact M8 the code generating relays CG, interrupting at contact 98 the connection of the 100 cycle source to the track rails through contacts of the code generating relays CG, and closing contact I68 to connect this source to the rails through one contact or another of coder CTE.

Relay TRF accordingly responds to the relatively rapid coding of the 100 cycle current, but the decoding relays CS and the code detecting relays CR are non-responsive to; such code rate so that relays I'lCR and 20GB; drop and indication lamps HF and AKF become dark. The operator at tower Q may now reverse lever V4, thereby supplying energy over contact Bl and contact memberZM of relay TRF to decoding transformer DTF, and decoding relays AJF, BJF and HF accordingly ar conditioned to pick up in accordance with the code rate of the received current. Signal lever V2 then may be operated to control signal WSF and permit a westbound movement.

In a further modification. the source of current at tower Q may be connected directly to contact member '84 of relay TRF" interposed in the energizing circuit of decoding transformer DTF and not, as shown, be taken through contact or 8| of levers V3 and V4, respectively. In such event, the decoding transformer DTP would normally be energized when current coded at the relatively low code rates of 20, 17, or 15 codes is received, but relays HF, BJF and AJF are non-responsive to suchc'ode' rates and hence are normally deenergized. However, when lever V! at tower P is reversed to acknowledge and permit a westbound move, then the increased rates of coding will cause relays HF, BJF and AJF to respond and pick up, and signal control lever V2 may be operated to control signal WSF toits caution or clear condition in accordance with the code rate of the received current. Trafll c lever V4 would normally be provided, however, and interlocked with lever V2 so that th latter lever could not be operated to its reverse position unless traffic lever V4 is first reversed.

If, now, with the apparatus of Fig. 2 in its normal condition as illustrated in the drawings, the operator at tower P wishes to send an eastbound train on track X toward tower Q, he may indicate the proposed traflic movement by depressing push button PB2, thereby altering the coding of the 100 cycle current from the combination 20-17 code to the 20-1'7-l5 code, as pointed out previously, and causing relay ICR at tower Q to pick up and illuminate indication lamp VKF. If conditions are favorable for an eastbound traffic movement, the operator at station Q may depress push button FBI to alter the coding of the 200 cycle current from the 180 code rate to the code rate, thereby deenergizing relays AJE and HE at tower P and causing indication lamp VKE to become illuminated to indicate that tower Q may receive the train, The operator at tower P may now operate lever V8 to its reverse position, thereby opening contact II'II to deenergize the code generating relays CG, openin contact 99 to disconnect from transformer TTE the 100 cycle source, and opening contact 85 and closin contact 86 to shift the tuning of rela TRE from the 200 cycle current to the 100 cycle current. Contacts I12 and I13 of lever V8 also close so that 2.00 cycle current is supplied to transformer TTE over one contact I20 or another contact I80 of coder C'I'E according as signal ESE is in its clear position or is in either its caution or stop position. When signal ESE is in either its stop position, as shown, or its caution position, contact I'I-I6 of controller J3E controlled thereby is closed, and 200 cycle current coded at the 180 code rate is supplied to transformer T'IE over a circuit extending from winding 42 of frequency changer FC through condenser 43, contact In of lever V8, contact lBIl of coder C'I'E, contact II-I6 of controller J3E, front contact I16 of relay TRD, contact I'I'I of lever V'I, contact I13 of lever V8 and winding of transformer TTE. If, however, signal ESE is cleared, then contact I8I"G of controller J3E closes and contact I20 replaces contact I80 of coder CTE in the just traced circuit.

This 200 cycle current supplied to section E-F is of course ineffective to operate relay TRF, and relay TRF drops so that all of the decoding relays associated therewith are released with the result that relay ARI also releases and indicators K15 and AKF become dark. When this happens, the operator at tower Q may reverse his eastbound trafiic lever V3, thereby opening contacts 89 and 93 to disconnect the 200 cycle source from transformer TTF, opening contact 81 and closing contact 88 to shift the tuning of relay TRF from the 100 cycle to the 200 cycle source, and closing contacts 90 and I15 to connect the 100 cycle source to transformer TTF over one contact or another of coder CTF. Relay TRF accordingly responds to the 200 cycle current received from the rails of section E-F and conditions relay HF and either relay BJF or AJF to be picked up, thereby energizing indicator KF, relay ARI, and causing indicator AKF to be energized. Lever VI may now be reversed to close its contact IBI, whereupon signal ESF clears. Rela TRE responds to the 100 cycle current received from the rails of section E--F to condition relays BSA, FSA, HE and AJE to be picked up according to the code rates at which the 100 cycle current is coded by coder CTF, this code selection being determined by the position of .signal. ESF. Signal lever V5 at tower P may now be operated to its reverse position to close its contact I82 and the signal will go to caution or clear according as signal ESF' is at stop, or is in its caution or clear position, respectively, to cause the 100 cycle current to be coded at the or the 180 code rate.

The eastbound train accordingly is permitted to move from tower P to tower Q, it being noted that cycle current is fed toward the train from the opposite end F of the section so that it is possible to control train-carried apparatus on the train by this 100 cycle current.

Lever V5 at tower Q is approach locked when the westbound train enters section D-E and relay 'IRD drops to disconnect the 2.00 cycle current from the track rails, this locking being attained in a manner explained in detail heretofore.

Signal ESE goes to stop when the train occupies section EF to shunt relay TRE, and the apparatus may be restored to normal after the train vacates section E-F .by restoring signal lever V5 and traffic levers V8 and V3 to their respective normal positions.

From the foregoing description, it is readily apparent that apparatus embodying my invention provides means whereby trafiie locking between towers may be effected without the use of line Wires by utilizing the track rails as transmission conductors. approach locking of trafiic controlling functions is effected without line wires. Furthermore, the apparatus incorporates means whereby track circuit current of the usual 100 cycle frequency is supplied to the stretch toward a train irrespective of the direction of its movement, thereby enabling train-carried apparatus on the train to be controlled.

Although I have herein shown and described only two forms of railway traflic controlling apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims Without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track including an insulated track section, two signals one at either end of said section for governing trafiic over said stretch in a given direction, a manually operable member controlling one of said signals, means governed by said one signal for controlling the supply of current of a particular character transmitted from a source at said one end of said section to said other end wholly over a track circuit comprising the rails of said section, means controlled by said particularly characterized track circuit current for controlling the other of said signals, means governed by said other signal for controlling the supply of current of another distinctive character transmitted from a source at said other end of said section to said one end wholly over a track circuit comprising the rails of said section, locking means for said manually operable member, and means controlled by said other distinctively characterized track circuit current for controlling said looking means.

2. In combination, a stretch of railway track including an insulated track section, two signals one at either end of said section for governing traffic in a given direction over said stretch, two sources of current having distinctively difierent characteristics one source at one end of the section and the other source at the other end, a manually operable member controlling the signal at said one end of said section, means controlled by said one signal for controlling the In addition, it is apparent thatsupply of current transmitted from said one source to the other end of said section wholly over a first track circuit comprising the rails of said section, means controlled by said first track circuit current for controlling the other of said signals, means controlled by said other signal for controlling the supply of current transmitted from said other source to theone end of said section wholly over a second track circuit comprising rthe rails of said section, means controlled w by said second track circuit current, and locking means for said manually operable member controlled by said last-mentioned means.

3. In combination, a stretch of railway track including an insulated track section, two signals 5 one at either end of said section for governing traflic in a given direction over said stretch, two sources of current having distinctively. different characteristics one source at one end of the section and the other source at the other end, a manually operable member for controlling the signal at said one end of said section, locking mean-s for said member, means controlled by said one signal for controlling the supply of current transmitted from said one source at said one end to the other end of said section wholly over a first track circuit comprising the rails of said section, means controlled by said first track circuit current for controlling the other of said signals, means governed by said other signal for controlling the supply of current transmitted 30 from said other source at said other end to the one end of said. section wholly over a second track circuit comprising the rails of said section, and means controlled by said second track circuit current for controlling said locking means, whereby said locking means is rendered efiective to lock said member unless said other signal occupies a proper restrictive position.

4. In combination, a stretch of railway track including an insulated track section, two signals one at either end of said section for governing traffic in a given direction over said stretch, two sources of current having distinctively different characteristics one source at one end of the section and the other source at the other end, a 15 manually operable member for controlling the signal at said one end of said section, locking means for said member, means controlled by said one signal for controlling the supply of current transmitted from said one source at said one 51) end to the other end of said section wholly over a first track circuit comprising the rails of said section, means controlled by said first track circuit current for controlling the other of said signals, means controlled by said other signal for controlling the supply of current transmitted from said other source at said other'end to the one end of said section wholly over a second track circuit comprising the rails of said section, means controlled by said second track circuit current for 'fgb,

controlling said locking means, and other means for controlling said locking means and governed by a time delay mechanism effective to impose a time delay in the control of said locking means.

5. In combination, a stretch of railway track 13;; divided into an advance and a rear track section, two signals one at either end of said advance section for governing traffic over said stretch from said rear section, a manually operable member for controlling the one signal at n; the exit end of said advance section, locking means for said member and effective when said one signal is cleared, control means for operating the other of said signals, means governed by said one signal for controlling said control -75 means by current transmitted from a source at said exit end to said entrance end wholly over a track circuit comprising the rails of said advance section, means for controlling said locking means by current transmitted from another source at said entrance end to said exit end wholly over a track circuit comprising the rails of said advance section and governed by said other signal to be effective to release said member only if said other signal occupies a proper restrictive position, and means governed by traific in said rear section for rendering said lock controlling means ineffective to release said member irrespective of the position of said other signal.

two signals one at either end of said' advance section for governing traffic over said stretch from said rear section, a manually operable member for controlling the one signal at the exit end of said advance section, locking means for said member and effective when said one signal is cleared, control means for operating the other of said signals, means governed by said one signal for controlling said control means by current transmitted from a source at said exit end to said entrance end wholly over a track circuit comprising the rails of said advance section, means for controlling said locking means by current transmitted from another source at said entrance end to said exit end wholly over a track circuit comprising the rails of said section and governed by saidother signal-to be effective to release said member only if said other signal occupies a proper restrictive position, means governed by traffic in said advance section for rendering said lock controlling, means inefiective to release said member irrespective of the position of said other signal, and means responsive to traffic in said rear section for approach energizing said one signal.

7. In combination, a stretch of railway track divided into an advance and a rear track section, two signals one at either end of said advance section for governing traffic over said stretch from said rear section, a manually operable member for controlling the one signal at the exit end of said advance section, locking means for said member and effective when said one signal is cleared, control means for operating the other of said signals, means governed by said one signal for controlling said control means by current transmitted from a source at said exit end to said entrance end wholly over a track circuit comprising the rails of said advance section, means for controlling said locking means by current transmitted from another source at said entrance end to said exit end Wholly over a track circuit comprising the rails of said section and governed by said other signal to be effective to release said member only if said other signal occupies a proper restrictive position and additionally governed by tralllc in said advance section for rendering said lock controlling means ineffective to release said member irrespective of the position of said other signal, and other means for controlling said locking means to release said member and effective at the end of a predetermined time delay interval.

8. In combination, a stretch of railway track including an insulated track section, signals at each end of said section governing trailic movements in one direction over said stretch, manually operable means for controlling the signal at the exit end of said section, two sources of distinctively characterized current one at each end of said section, means governed by said exit end signal for supplying to the rails at the exit end of said section current from one of said sources coded at one code rate or another in accordance with the position of said exit end sign 1, means receiving energy from the rails at the ntrance end of said section and selectively res controlling the signal at said entrance end in accordance with the code rate of the received current, means governed by said entrance end signal for supplying to the rails at said entrance end of said section current-from the other of said sources coded at one code rate or another in accordance with the position of said entrance end signal, other means receiving energy from the rails at said exit end of said section and selectively responsive to current from said other source, and lock means for said manually operable means controlled by said other means for preventing a movement of said manually operable means when said entrance end signal occupies a predetermined position as indicated by said other means responding to current from said other source coded at a particular one of said code rates.

9. In combination, a stretch of railway track including a track section, two signals governing traflic in one direction over said stretch and positioned respectively at opposite ends of said section, a first source of alternating current at the exit end of said section, a second source of alternating current at the entrance end of said section having a frequency different from the frequency of said first source, a track relay at each end of said section responsive only to current of the frequency supplied at the opposite end of said section, means governed by the signal at the exit end of said section for supplying current from said one source to the rails at said exit end of said section coded at one or another of a plurality of code rates in accordance with the position of said exit end signal, means responsive to the code rate of operation of the track relay at said entrance end for controlling the position of the other of said signals, means controlled by said other signal for supplying current from said other source to the rails at said entrance end of said section coded at one or another of said plurality of code rates in accordance with the posi tion of said other signal, a manually operable lever for controlling the position of said one signal, and lock means for said lever controlled by the track rela at said exit end of said section.

10. In combination, a stretch of railway track including a track section, two signals governing trafiic in one direction over said stretch and positioned respectively at opposite ends of said section, a first source of alternating current at the exit end of said section, a second source of alternating current at the entrance end of said section having a frequency different from the frequency of said first source, a track relay at each end of said section responsive only to current of the frequency supplied at the opposite end of said section, means governed by the signal at the exit end of said section for supplying current from said one source to the rails at said exit end of said section coded at one or another of a plurality of coderates in accordance with the position of said exit end signal, means responsive to the code rate of operation of the track relay at nsive to current from said one source for 1 said entrance end for controlling the position of the other of said signals, means controlled by traflic conditions in the rear of said other signal and by said other signal for supplying current from said other source to the rails at said entrance end of said section coded at one or another of said plurality of code rates in accordance with the position of said other signal, a manually operable lever for controlling the position of said one signal, code responsive means controlled by the track relay at said exit end of said section, and lock means for said lever controlled by said code responsive means. I

11. In combination, a stretch of railway track, two signals at each end of said stretch one for governing traffic in one direction and the other for governing traffic in the opposite direction, a first manually operable control means at one end of said stretch for establishing control of the signals governing trafiic in said one direction and a second manually operable means at the other end of said stretch for establishing control of the signals governing trafiic in said opposite direction, a first control means at said other end of said stretch for controlling the operation of the signal governing traffic in said one direction at said other end, other control means at said one end of said stretch for controlling the operation of the signal governing traffic in said opposite direction at said one end, means controlled by said first manually operable control means for controlling said first control means by current transmitted from said one to said other end of said stretch wholly through a track circuit comprising the rails of said stretch, and means controlled by said second manually operable control means for controlling said other control means by current transmitted from said other to said one end of said stretch Wholly through a track circuit including the rails of said stretch.

12. In combination, a stretch of railway track, two signals at each end of said stretch for governing trafiic in opposite directions, one signal at each end being a rear signal governing traffic in said stretch and the other signal being an advance signal, a first control means at one end of said stretch for establishing control of the rear signal at said one end and its associated advance signal, a second control means at the other end of said stretch for establishing control over the rear signal at said other end and its associated advance signal, two track circuits for said stretch a first comprising a first source of distinctively characterized current at said one end and a first track relay at said other end uniquely responsive to said distinctively characterized curent and the second comprising a second source of differently characterized current at said other end and a second track relay at said one end uniquely responsive to said differently characterized current, means governed by said first control means and other means governed by the advance signal at said one end for controlling the energization of said one track circuit by said first source, means governed by said first track relay for controlling the advance and rear signals at said other end of said section, means governed by said second control means and other means governed by the advance signal at said other end for controlling the energization of said second track relay by said second source, and means governed by said second track relay for controlling said advance and rear signals at said one end of said stretch.

HERBERT A. WALLACE. 

